This invention relates in general to hybrid circuits used in the construction of radio equipment and the like. More specifically, this invention relates to packaging and interconnect systems used in the fabrication of hybrid circuits.
The use of ceramic substrate thick and thin film hybrid circuits is becoming more and more widespread in the radio communications industry. Such circuits generally are used in the construction of subsystems that are electrically connected with other such systems and/or conventional components placed on printed wire boards (PWB).
Hybrid circuits are formed on a ceramic substrate. Various components, such as capacitive and resistive elements are "painted" onto this substrate using silver poladium or some other "ink" forming a conductive or semiconductive layer. For capacitive elements a dielectric layer is "painted" between two conductive layers. The size of the layers, spacing and dielectric properties determine the capacitance of the element. In addition, lumped parameter conventional components such as resistors, chip capacitors, and inductors may form part of the circuit, hence the term "hybrid".
As the radio spectrum becomes more crowded and frequency tolerances become more severe; and as radio equipment becomes more sophisticated, there is an increasing need for a packaging system that can protect their delicate ceramic substrate and the electrical components mounted and painted thereon while providing a high degree of radio frequency (RF) interference shielding to meet the performance requirements of radio communication equipment. In addition, it is highly desirable to provide a circuit interconnection system allowing the quick and easy substitution of one ceramic hybrid circuit for another.
A known hybrid circuit packaging arrangement is shown in U.S. Pat. No. 4,001,711--Knutson et al, incorporated herein by reference. This is a high power level circuit and includes pins that are soldered directly to a printed wire board when the hybrid circuit is installed. Although such solder interconnection may be required for high power circuits requiring heat dissipation through the pins, this known packaging arrangement is inappropriate for most small signal applications. The use of solder in terminals is unnecessarily restrictive, both in initial assembly of a piece of radio equipment and in servicing it.